Noveske rifleworks extreme duty machine gun barrel

ABSTRACT

An improved method for producing barrels which need to operate at temperatures exceeding 800 degrees for prolonged periods of time. The method described is ideally suited for barrels which are a part of a crew served weapons, belt feed systems or other fully automatic weapons. My method has limited effect on the accuracy potential of the barrel produced and therefore should not be excluded from use on shoulder fired weapons and precision rifles.

CROSS-REFERENCED TO RELATED APPLICATIONS

This application claims the benefit of PPA Ser. No. 60/899,784, filedFeb. 5, 2007 by the present inventor.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention generally relates to firearms, specifically tomanufacturing processes for strengthening firearm barrels to withstandtemperatures exceeding 800 degrees Fahrenheit during the course of anextending firing schedule.

2. Prior Art

Barrels for firearms are traditionally manufactured from various allowsof steel. Lining barrels with various foreign materials in order toprovide resistance to corrosion, increased velocity and long servicelife has been a routine practice for small arms during the past 100years.

416 stainless steel has been used to prevent corrosion but is generallynot as well suited for use as a firearm barrel as compared to the 4140and 4150 chrome molly steel. 4140 and 4150 are very popular for use inmilitary small arms such as the Colt M16.

During the United States involvement in Vietnam barrel bore rustingcaused weapon malfunctions. 4150 chrome molly steel barrels would rustin the humid environments. Further the small, high pressure projectilewhich the M16 fired eroded the chamber of the barrel rapidly. A chromelining was applied to the barrel in order to extend the service life ofthe weapon.

Chrome lined barrels present several problems. First it is verydifficult to apply the chrome evenly for large production runs. As aresult accuracy of the host weapon suffers. Chrome lining does not allowthe barrel to operate at temperatures over 800 degrees for any prolongedperiod of time.

Other ideals such as composite gun barrels as depicted in U.S. Pat. No.6,889,464 offers a light weight alternative which cools faster than astandard barrel. Unfortunately the resins used in the construction arenot suitable for sustained high rates of fire. Eventually due to highheat the resin will break down rendering the barrel unusable.

Firearm barrels which are exposed to temperatures exceeding 800 degreesfor a prolonged time will loose temper quickly eroding the barrelchamber. This results in the firearm malfunctioning.

Other linings such as described in U.S. Pat. No. 7,197,986 are notuseable with stainless steel barrels. The proposed invention of theabove referenced patent does nothing to increase the strength of thebarrel at higher temperatures. The coating described is limited toprotecting the chamber and rifling of the barrel. When a firearm isbeing operated for prolong periods of time at high temperatures thetemper of the barrels its self is the primary problem to over come.

OBJECTS AND ADVANTAGES

Accordingly several objects and advantages of the present invention are

-   -   (a) To provide a process which will enhanced corrosion        resistance to both chrome moly and stainless steel barrels    -   (b) To provide a process which will extended barrel service life        by protecting the surface of the chamber and rifling of a        firearm barrel    -   (c) To provide a heat treat process which will allow the barrel        to maintain its temper at high temperatures    -   (d) To provide a oxidation layer which will minimize friction        between the barrel chamber and a spent cartridge    -   (e) To provide a oxidation layer which will reduce friction        between the bore and a discharged projectile    -   (f) To provide a process which may be applied to a variety of        steel    -   (g) To provide a oxidation layer around the gas port to as to        extend the service life of auto loading rifles

Still further objects and advantages will become apparent from aconsideration of the ensuing description and drawings.

SUMMARY

This invention is in answer to the steady increase of the use of hotterburning gun powder for performance and the full automatic utilizationfor more rounds per minute. Both characteristics have continued to pushthe gun barrel life to the limit with regard to hot strength and barrelerosion. Until now, many attempts have been made to improve barrelperformance with insufficient success. It is safe to say that gun barrelperformance has been one of the primary limits to the increase of gunfirepower.

A new method for increasing gun barrel performance is disclosed hereinand is more than simply a gun barrel coating or lubricant. The presentinvention is a simple but effective method for enhancing the performanceof the gun barrel itself and introduces additional benefits notedherein.

One object of the present invention is the composite hardening of thebarrel. The barrel is initially hardened to HRC 50-55 after thechambering and machining process are complete.

Another object of the present invention is to provide a simple butmeaningful method of improving the metal of the gun barrel with a liquidsalt dip nitride surface conversion which tempers the barrel steel andleave a black oxide surface layer which is extremely resistance tocorrosion. This process does not add significantly to the dimensions ofthe barrel.

While the interior and exterior of the barrel are being oxidized throughthe process of a liquid salt dip those same surfaces are also being heattreated to a HRC 68-72 to a depth of fifteen thousandths of an inch.

The method I am describing as novel creates a core barrel hardness ofHRC 50-55 and a diffusion layer about fifteen thousands deep on theinterior surface of the barrel which is HRC 68-72. This diffusion layerwill extend the life of the barrel as compared to popular coatings suchas chrome lining. As the surface oxidation erodes the bare metalunderneath is harder than the metal present under a chrome lining.

My method is superior to coatings because it is actually changing theproperty of the barrel steel and is not limited to what types of steelmay be processed.

DRAWINGS

The novel features believed to be characteristic of the invention,together with further advantages thereof, will be better understood fromthe following description considered in connection with the accompanyingdrawings in which a preferred embodiment of the present invention isillustrated by way of example. It is to be expressly understood,however, that the drawings are for the purpose of illustration anddescription only and are not intended as a definition of the limits ofthe invention.

FIG. 1 is a longitudinal sectional view of various layers of metal whichin the preferred embodiment is a firearm barrel;

FIG. 2 is a sectional side view of the preferred embodiment chamberlocated on a firearm barrel;

FIG. 3 is a sectional side view of the muzzle on the preferredembodiment firearm barrel;

FIG. 4 is a block diagram illustrating one set of steps used in makingthe extreme duty machine gun barrel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As used herein, the word “front” or “forward” corresponds to the firingdirection of the firearm (i.e., to the right as shown in FIGS. 1, 2 and3); “rear” or “rearward” or “back” corresponds to the direction oppositethe firing direction of the firearm (i.e., to the left as shown in FIGS.1, 2 and 3); “longitudinal” means the direction along or parallel to thelongitudinal axis a of the barrel of the firearm; and “transverse” meansa direction perpendicular to the longitudinal direction.

In FIG. 1, there is shown a longitudinal sectional view of a compositeof harness layers of a firearm barrel 1, which in the preferredembodiment is a M4 carbine gun barrel having a breech end 5, a muzzleend 6, an inner and outer black oxide surface coating 2, and andiffusion layer 3. In the preferred embodiment, the firearm barrel 1 isH13 tool steel or other hard refractory material such as for example4150 carbon steel or a 400 series stainless steel. It has internal wallsforming a central longitudinally extending bore 7 which may have riflingon the inside. In the preferred embodiment, the black oxide surfacelayer 2 comprises all surfaces which are external in that they are incontact with the external environment. The diffusion layer 3 comprisesbarrel 1 material which begins at a depth of one thousandth from thesurface of the firearm barrel 1. The black oxide surface layer 2 alsocoats the interior of the gas port 4.

In FIGS. 2 & 3, there is shown a longitudinal sectional view of thefirearm barrel 1 chamber 5 and muzzle 6. Illustrated is the contiguoussurface protection afford by the black oxide coating 2. Also depicted isthe diffusion 3 which is surrounded on all sides by the salt nitridelayer.

In FIG. 4, there is shown a flow diagram of a process 20 for producingthe Noveske Rifleworks Machine Gun Barrel 1 which is designed to offerthe machine gun user the option to operate the weapon at highertemperatures than normally allowed with the current machine gun barreloptions. This is accomplished with the use of our proprietary barrelmaterial, the hardening process, and the final surface conversionprocess. The barrel 1 is made using H13 tool steel in the softenedmachinable state. Once the barrel 1 has been machined 10, the bore ishand lapped using a lead lap 11 impregnated with aluminum oxideparticles to orient the land and groove surfaces with the helical twistof the rifling. This process insures that no mechanical abrasion willoccur on the projectile as a result of its travel down the bore. Thislapping 11 process is also a critical step for the surface conversionprocess which will be covered later in this description.

Next, the barrel is chambered 12, a term which describes the removal ofbarrel material at the rear which results in the negative of a firearmcartridge. A cartridge is the assembled unit comprised of a case,primer, propellant, and projectile. The barrel 1 now is ready forhardening. The H13 tool steel is hardened to HRC 50-55 13. Then thebarrel 1 is subjected to a unique process which is a liquid salt dipnitride surface conversion 14 which also tempers the hardened barrel 1.The end result is a barrel 1 with a blackened oxide surface 2 which isextremely resistant to oxidation and other forms of corrosion. Also, theblackened oxide surface 2 is very slick which affects the chamber 5 byimproving extraction and affects the bore by reducing friction on theprojectile. The nitrided surface extends the serviceable life of thebarrel 1 in that it the surface of the barrel material is transformedinto a very hard and durable state, about HRC 68-72. This hardenedblackened oxide surface 2 will wear slower than a coating, and is not assensitive to fluxuations in temperature as coatings such as hard chrome.The blackened oxide surface 2, or nitriding process hardens the surfacefor about one thousandth of an inch, and also hardens the material underthe surface for about fifteen thousandths of an inch. This secondarylayer is called the diffusion layer 3. The diffusion layer 3 offers anextended barrel life over current hard chrome lined barrels in that asthe hardened blackened oxide surface 2 layer erodes, the tooth-likeportion of the bore, the lands, are still harder in their core than thecore of the fore mentioned hard chrome lined barrels. The diffusionlayer 3 also offers an improved resistance to corrosion than the wornand exposed barrel material used in the hard chrome lined barrel. Thenitrided surface is an improvement over hard chrome in this regard inthat it is not a coating, but a transformation to the existing material,(H13). This process may be applied to many types of barrel steel.

Thus, there has been described a preferred method for the production ofmy extreme duty machine gun barrel. My method prepares a barrel 1 tooperate at temperatures up to 1000 degrees with out fear of the barrel 1loosing its temper. The bore 7 and chamber 5 of the barrel will resisterosion from the high heat and pressure producing a barrel with superiorduty cycle over other barrels which are coated with chrome ormanufactured using other currently available methods. My method ofmachining 1 the lands and grooves of the barrel, heat treating the basebarrel material to provide a HRC 50-55 13, and finally salt nitridedipping 14 the barrel to provide a surface and diffusion layer which isHRC 68-72 and resistant to corrosion may be adapted to work withstainless steel and other tool steels commonly available such as 4140and 4130 chrome moly. Other embodiments of the present invention, andvariations of the embodiment described herein, may be developed withoutdeparting from the essential characteristics thereof. Accordingly, theinvention should be limited only by the scope of the claims listedbelow.

CONCLUSION, RAMIFICATIONS, AND SCOPE

Accordingly the reader will see that, according to the invention, I haveprovided a barrel which is capable of extended duty cycles weretemperatures may exceed 800 degrees Fahrenheit. Further is can bee seenthat my process of manufacture and method of production may be appliedto a wide variety of metals which are suitable for use as firearmsbarrel. I have also afforded the user of barrels produced by my methodthe opportunity to use their firearms for firing schedules which woulddestroy or significantly reduce the useful life of other currentlyavailable barrel.

While my above drawings and description contain many specificities,these should not be construed as limitations on the scope of theinvention, but rather as an exemplification of one preferred embodimentthereof.

Accordingly, the scope of the invention should be determined not by theembodiments illustrated, but by the appended claims and their legalequivalents.”

1. A method for creating a firearm barrel with a surface hardnesscomprising a coating and surface hardness which is harder than the subsurface of the barrel: a. providing a steel suitable for a firearmbarrel which is capable of bonding with salt nitride, and b. providing amanufacturing process which will prepare the interior of a firearmbarrel to be coated with salt nitride, and c. initial heat treat of thefirearm barrel prior to salt nitride coating, and d. salt nitridecoating the firearm barrel after said heat treating, Whereby said barrelis highly resistance to corrosion, erosions from heat and warping due toextended duty cycles.
 2. A method for creating a firearm barrel with asurface hardness comprising a coating and surface hardness which isharder than the sub surface of the barrel as set forth in claim 1,wherein said firearm barrel is machined from 4130, 4140, 4150, 416stainless, 17-4 stainless or H13 tool steel.
 3. A method for creating afirearm barrel with a surface hardness comprising a coating and surfacehardness which is harder than the sub surface of the barrel as set forthin claim 1, wherein said manufacturing process provides a means forlapping said barrel with a lead lap impregnated with aluminum oxideparticle,
 4. A method for creating a firearm barrel with a surfacehardness comprising a coating and surface hardness which is harder thanthe sub surface of the barrel as set forth in claim 1, wherein saidinitial heat treat process hardens the barrel to HRC 50-55
 5. A methodas set forth in claim 1, wherein said salt nitride provides a heat treatand surface coating which is harder than said initial heat treat
 6. Themethod for creating a firearm barrel with a surface hardness comprisinga coating and surface hardness which is harder than the sub surface ofthe barrel as set forth in claim 5, wherein said salt nitride provides asurface coating consisting of carbon and nitrogen commonly referred toas Melonite.
 7. The method for creating a firearm barrel with a surfacehardness comprising a coating and surface hardness which is harder thanthe sub surface of the barrel as set forth in claim 5, wherein said saltnitride serves as a heat treat process for the surface and immediate subsurface of the barrel providing a temper of HRC of 68-72.
 8. The methodfor creating a firearm barrel with a surface hardness comprising acoating and surface hardness which is harder than the sub surface of thebarrel as set forth in claim 7, wherein said salt nitride serves as aheat treat process and coating effectively creating a surface layer ofsteel which is harder than the center of the firearm barrel.